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An early PostgreSQL implementation in Go
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gosql

An early PostgreSQL implementation in Go.

Example

$ git clone git@github.com:eatonphil/gosql
$ cd gosql
$ go run cmd/main.go
Welcome to gosql.
# CREATE TABLE users (name TEXT, age INT);
ok
#  INSERT INTO users VALUES ('Stephen', 16);
ok
# SELECT name, age FROM users;
   name   | age
----------+------
  Stephen |  16
(1 result)
ok
# INSERT INTO users VALUES ('Adrienne', 23);
ok
# SELECT age + 2, name FROM users WHERE age = 23;
  age |   name
------+-----------
   25 | Adrienne
(1 result)
ok
# SELECT name FROM users;
    name
------------
  Stephen
  Adrienne
(2 results)
ok

Architecture

  • cmd/main.go
    • Contains the REPL and high-level interface to the project
    • Dataflow is: user input -> lexer -> parser -> in-memory backend
  • lexer.go
    • Handles breaking user input into tokens for the parser
  • parser.go
    • Matches a list of tokens into an AST or fails if the user input is not a valid program
  • memory.go
    • An example, in-memory backend supporting the Backend interface (defined in backend.go)

Contributing

  • Add a new operator (such as <, >, etc.) supported by PostgreSQL
  • Add a new data type supported by PostgreSQL

In each case, you'll probably have to add support in the lexer, parser, and in-memory backend. I recommend going in that order.

In all cases, make sure the code is formatted (make fmt) and passes tests (make test). New code should have tests.

Blog series

Further reading

Here are some similar projects written in Go.

  • go-mysql-server
    • This is a MySQL frontend (with an in-memory backend for testing only).
  • ramsql
    • This is a WIP PostgreSQL-compatible in-memory database.
  • CockroachDB
    • This is a production-ready PostgreSQL-compatible database.
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